Congratulations Nicholas on your first review! As speculated in the PSU forum, the benefit of the heatpipes is not fully captured because of dense fin arrangement, and efficiency is low in the sub-100W area, as one might expect. Also fan controller is disappointingly unsophisticated, probably just thermistor-based.

@jaganath - Thanks for your support. It's a pleasure to be part of the team.

Yes, you're right about the fins on the heatpipes. They're far to tightly spaced for a low airflow environment. The fan controller doesn't really seem like much of a controller either... other quieter power supplies tend to keep the fan speed as low as possible for as long as possible, but will ramp up the speed when needed.

@roadie - A pass through fan system might have helped direct airflow past the heatpipes more, but then there's still the problem of the fan controller.

Well based on what I've read I'd say those heatpipes are working as they are intended. The main heatsinks are significantly smaller than say in S12/S12+, and yet temperature rise is about the same, so in all the likelyhood heatpipes do transfer enough heat to offset smaller heatsinks.

However, it's still a rather disappointing power supply from silent perspective. For one, because of crude fan controller that ramps up way too soon, and two, because it would seem that while heatpipes do work, conventionally cooled power supplies work just as good, so there is really no point in using heatpipes as they offer no advantages over regular PSUs (other than making PSU longer by 2.5cm which can create problems for cases like P180).

To extend the discussion that began in the New Zalman 600W Modular PSU thread, I'd have to say the heatpipes seem more like a marketing decision than an engineering one. Not to say that they don't work as intended; just that more conventional methods would have worked just as well. In general, if the distance the heat is moved by heatpipes is no more than a couple of inches, and if the transfer of heat does not increase the exposure to airflow significantly, then there's little to be gained.

Contrast this heatpipe/HS to tall CPU heatsinks in which heatpipes provide more effective distribution of heat to a much greater number of fins, or to the CPU HS used in some of the Shuttle SFF systems where the CPU is almost the entire depth of the case away from the fins of the heatsink. (The SD11G5, for example -- it moves the CPU heat from the front/middle of the case to the very edge of the back panel where it is easily evacuated by the fan without heating up any other part of the system.) Those are very effective uses of heatpipes.

I don't believe the Zalman heatpipe addresses the hot air pocket issue in 120mm fan PSUs that the Seasonic M12's 60mm fan is meant to do, either... though that solution is not exactly ideal from an acoustics viewpoint. (It would be much better if the 60mm fan actually turned back off again.)

In any case, the fan controller is a step back to earlier Zalman PSUs (pre-zm460) , which always seemed to have cooling as a higher priority than lowest noise. That this approach re-emerges in a 600W PSU is not the worst thing. Most users who actually need a 600W PSU probably don't need anything quieter, because the rest of their components will drown this Zalman out anyway.

Pardon my lack of knowledge, but doesn't the mosfets on the primary side generate a good amount of heat as well? From what I see the heatpipe is only for the secondary side.

The heat generated in the semiconductors and all the other components comes from their internal resistance (R) and the current (I) they are passing; the formula is (I^2)*R (i.e. Current squared times the internal resistance)

Without going into excessive detail; for any given load, the bits on the high voltage side (typically 400v) are carrying less current than the bits on the low voltage side (3.3, 5 and 12v).

The heat generated in the semiconductors and all the other components comes from their internal resistance (R) and the current (I) they are passing; the formula is (I^2)*R (i.e. Current squared times the internal resistance)

Without going into excessive detail; for any given load, the bits on the high voltage side (typically 400v) are carrying less current than the bits on the low voltage side (3.3, 5 and 12v).

The formula is also V^2/R, or IV; this 3 formulae are interchangable by the substitution V=RI

If V is high, I has to be high or R has to be high if you were to keep I low. Actually R is the determining factor here since V is known and fixed and I is a dependant variable.

Formulae aside, in most PSUs the primary side has heatsinks almost the same size as that on the secondary, shouldn't that be saying something about the heat output?

While you are quite correct, you ought to point out that the V in the above equation is the voltage across the resister (internal resistance in case I was discussing) and not the voltages of the input or output.

Quote:

Actually R is the determining factor here since V is known and fixed and I is a dependant variable.

Well yes, R is the determining factor, but V is certainly not fixed (hang a 'scope on the switching tranny!) and while I is load dependent, it is not a simple relationship.

The original discussion was why the heat pipe was used on the low voltage side heat-sink, and that is because the low voltage side is passing more current, thus generating more heat (in the case where the internal resistances of the components on either side of the transformer are both small and comparable).

The reason the two heatsinks are often of similar size is because there is a greater potential loss in the switching transister (making it's effective internal resistance higher). As the efficiency of the psu is improved, it is the switching circuit side that benefits. Hence, the greater need in this design to cool the low voltage side than the hv side.

Could I please know if the fan of this unit can be swapped.
After going through hundreds of reviews all over the net, I haven't found a single pic that shows if the fan is plugged (as in the 460w model) or welded.

I've just swapped the fan in my ZM600HP to a scythe S-FLEX 1600rpm. The fan is soldered with two wires, but it is a easy task to just cut the wires and solder the ends to the Scythe fans + and - wires.

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